Photo search with PureMVC in AS3

Since I have promised to share a PureMVC
site template a long time ago, and it is still bound to happen, I will now share another project I also built using the aforesaid framework.

This little project was built about four months ago, to solve a skill test for a Senior Flash Developer position in a London based agency. It took around 10 hours to complete during after-work time. A working demonstration is available here: http://demo.joaopescada.com/searchable-image-gallery/
.

The visual side of the application was also important. And, in my opinion, this is a point that marks a great difference between “hardcore” developers — with strong technical skills but, usually, low sensibility to visual design – and front-end developers in general, where a Flash Developer should be included. Any good front-end developer should comfortably know the elements and principles of design
.

Take time defining the problem, and then solve it fast.

Having recently learned how to use PureMVC, this test seemed like a great way to strengthen my experience with the framework. It was fairly simple and only had to implement a couple of basic actions: show the photos with or without a tag filter applied and show each photo in detail.

For the visual layout, I opted for a grid-less structure simulating a real life environment: a wood floor with the photos scattered all over. It wasn’t the most common solution, but it was still easy to use and hopefully eye-candy enough to stand out from the crowd (the other developers applying for the same position).

The architecture.

As any regular MVC
project, the classes needed to be grouped in three folders / packages: model
(storing all the data that the app will need), view
(where anything-visual is kept and the user actions are captured) and controller
(providing communication between view
and model
).

The stage was created in a single Flash file using the Main
class as the document class, with all the visual assets in the library being linked to classes in the view
package.

Startup and the Controller.

It all starts in the Main
class in the app
package. As soon as the stage is available, the AppFacade
singleton is fired, initialising the PureMVC framework, overriding the sendNotification
method — to allow debug control, by tracing the notification arguments — and registering the possible controller command calls with specific notifications:

– the StartupCommand
is triggered by the STARTUP
notification. It registers and initialises the data sources available ( StageProxy
, StateProxy
and PhotosProxy
), and the AppMediator
(attaching it to the stage) and then requests a new photo search, without any filter applied, to populate the initial layout.

– the PhotoSearchCommand
will listen for PHOTO_SEARCH
notifications, handling all searches, through the PhotosProxy
.

– the PhotoDetailCommand
will respond to SHOW
and HIDE
notifications, setting the app state using the StateProxy
, and showing or hiding the detail of a photo.

The Model.

The StageProxy
allows access to the app stage, and dispatches notifications every time the stage is resized.

The StateProxy
works as a central point to store information about the current state of the app. Namely the current photo selected, if any, and dispatches notification when the state is changed.

The PhotosProxy
loads and provides methods to access the information stored in the XML, like search
and returns the result coupled to a PHOTO_SEARCH_RESULT
notification.

And the View.

The AppMediator
registers mediators for the visual components of the layout: the GalleryMediator
, the SearchBoxMediator
and the DetailMediator
.

The GalleryMediator
controls the gallery
movieclip on the stage, that will load and display the photo thumbnails. It subscribes to PHOTO_CHANGED
, PHOTO_SEARCH_RESULT
and STAGE_RESIZE
notifications in order to update the gallery
movieclip as needed. It also listens for clicks in the photo thumbnails and dispatches notifications to the AppMediator
when it happens.

The SearchBoxMediator
holds a reference to the searchBox
movieclip on the stage. It subscribes to PHOTO_SEARCH_RESULT
and STAGE_RESIZE
notifications and dispatches a PHOTO_SEARCH
notification when the user submits the search.

The DetailMediator
is linked to the detail
movieclip on the stage, updating the display when the subscribed notifications PHOTO_CHANGED
or STAGE_RESIZE
are received, and dispatches a PHOTO_HIDE
notification when the user clicks on the detail
movieclip.

All the visual components in the library linked to classes in the app.view.components
package have simple methods to update the display or dispatch custom events that will then be picked up by the associated mediators and processed as need be.

Wrapping up.

This was an overview of the logic behind the app.

Feel free to browse and change the code to see what happens and learn with it.

If you end up facing problems or doubts, just drop me an email or comment using the form bellow and I will happily give you all the help needed.